1. Field of the Invention
The present invention relates to a W-CDMA (Wideband-CDMA) system, and more particularly, to an antenna sharing apparatus of a base station for sharing an existing antenna in case of increasing a frequency allocation.
2. Description of the Background Art
In general, a W-CDMA system provides a voice and a data communication service. A channel signal transmitted from a terminal is transmitted through various radio paths to a base station.
At this time, an interruption occurs between signals having different receiving paths among signals transmitted from the base station, causing a fading phenomenon that an attenuation rate varies as time elapses, which triggers an error of a reception signal in the base station.
Therefore, in order to minimize such a fading phenomenon, the base station synthesizes an output of an antenna by a space diversity method, that is, by using two reception antennas.
If a resource at a frequency band for service is not sufficient, the frequency bands (FA), a plurality of communication channels, are positioned mutually adjacent without a guard band.
Accordingly, unlike a PCS system having the guard band, the WLL-CDMA system separately installs a transmission-reception antenna by frequency bands and operates it.
FIG. 1 is a drawing illustrating a related art antenna sharing apparatus of a base station using a single frequency band.
As shown in FIG. 1, a conventional antenna sharing apparatus of a base station includes a transmission-reception antenna 10, a receiving dedicated antenna 12 and a duplexer 20.
The antenna 10 is used as a transmission antenna, while the antennas 10 and 12 are used as the first and the second reception antennas for a space diversity.
Since the antenna 10 can be used both for transmission and reception, the duplexer 20 separates a transmission signal (Tx1) and a reception signal (Rx1) by using a filtering function. That is, the duplexer 20 outputs a transmission signal (Tx1) provided from the base station to the antenna 10, and outputs the reception signal (Rx1) inputted through the antenna 10 to the base station.
Accordingly, the base station synthesizes the reception signals (Rx1 and Rx1xe2x80x2) inputted through the antennas 10 and 12 to prevent the fading phenomenon.
Generally, the WLL-CDMA system is allocated a specific frequency and provides a radio communication service to subscribers.
At this time, the radio frequency allocation is made in consideration of the number of expected subscribers, and the radio frequency is additionally allocated according to change in the number of the subscribers.
Accordingly, in case that a frequency allocation is additionally made in line with an increase in the number of the subscribers, the antenna needs to be additionally installed corresponding to the added frequency allocation.
For example, if a single frequency band (1 FA) is used, as shown in FIG. 1, two antennas are required. If two frequency bands (2 FA) are used, as shown in FIG. 2, two more antennas need to be installed.
In this manner, whenever the FA is increased, two antennas are additionally increased, causing a problem that an antenna installation cost is additionally incurred due to the increasing number of antennas.
In addition, in the conventional antenna sharing apparatus, between the duplexer 20 and the antennas 10 and 12 is a wired section to be connected by a cable directly by a person.
Consequently, in consideration of the fact that the WLL-CDMA system is installed and operated in an area where a wired telephone network is hardly adopted, additional installation of the antenna in line with the increase in the frequency allocation is practically difficult.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.
Therefore, an object of the present invention is to provide an antenna sharing apparatus of a base station in a W-CDMA system that is capable of reducing an expense by minimizing the number of antenna in case of additional frequency allocation.
To achieve at least the above objects in whole or in parts, there is provided a W-CDMA system including a plurality of antenna sharing apparatuses of a base station having a LAN for receiving a first reception signal for a space diversity from a transmission-reception antenna, low-noise amplifying it and separately outputting it to a first and a second paths, and a band-pass filter for filtering a second reception signal for a space diversity, wherein the second path of each antenna sharing apparatus is connected to an input terminal of the band-pass filter of a different antenna sharing apparatus.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.